As far as aliens, well, they are stored somewhere else. I happen to know someone who worked for a place here in western NY that said they used to have one in "cold storage" in one of the lower levels of their government contract building. The specimen was later transfered to another facility which was not disclosed to even the higher authorities in the facility. This person currently holds the highest civilian security clearance available.

Now, I usually would doubt someone telling me things like this, but this particular person has never led me astray. They are completely trustworthy.